I need to plan NOW to do it later. Even with the grid, how would you heat and cool? Why spend $$$ you don't need to? Failure to plan ... see it daily.
I think based on simplicity, I highly recommend the high-SEER rated mini-split HVAC solutions (for their ease of installation and incredible efficiency). I have installed two of them (mine happened to be Mr Cool brand, since I wanted the pre-charged line-sets for even easier installation). I installed a single-head unit for my insulated shop, and a 4-head unit for my brother-in-law's home, and can testify to their efficiency. If it gets really cold over there, you want to look into the newest style, latest-gen units which are designed to operate well and efficient even down to and even beyond -10 degrees F...
Everybody knows there’s no such thing as zero degree heating when it comes to a heat pump. An energy efficient heat pump might work for mild temperatures, but they rapidly lose efficiency as the temperature drops. Everybody knows you need a gas furnace to stay warm in severe winter weather...
mrcool.com
My Mother also has a 4-head Daikin mini-split in her house for 15 years now, and she says it has saved her a ton of money over the years. They're also very quiet, you barely notice any sound from them, just a quiet whish kind of air noise if they spin-up a little more sometimes.
But mini-splits use inverter technology and have all DC variable speed motors for their fans and compressor so they can spin them down very slow and only ramp up and down the speed gradually, depending on realtime demand. They are also most friendly running on battery power, inverters and such, since they only soft-start, and don't draw much a lot of the time.
Engineer775 on You Tube has some good videos on mini-splits for off-grid or solar environments. He's even installed some of the native-DC 48v ones that can run right off raw battery bank power...
The first type (like mentioned above) are the traditional ones where they use air-to-freon condenser units mounted outdoors and are subjected to normal outdoor ambient temperatures.
Then they have other style mini-split setups where the condenser unit can exchange heat from antifreeze liquid pipes running underground (a type of geo-thermal piping system), so that the condenser is more subjected to the average year-round temperatures found underground (instead of contending with ambient outdoor temps to interact with). That type is best for arctic temperatures, below -10 degrees F, or just make for even higher efficiency in mild environments.
The latter type, is more costly and requires more yard, as it requires lengthy, or deep piping, and the associated excavating costs.
Mini-split technology can also tie into hybrid hot water heaters and be used to heat water, and whatnot. Worth looking into as well.